GASTEROPODA OF THE LOWER GREEN MARLS. 167 
fourteen on the entire shell. On the larger or outer third of the .shell’s 
length the surface is marked only by fine transverse lines of growth, the 
longitudinal ridges becoming obsolete below and the shell presenting a semi- 
polished structure. No slit or groove can be detected in the shell, or indi- 
cation of such feature on any of the casts, consequently the shell appears 
to be a true Dentalium. On the interior of a second specimen which pre- 
serves the shell and is broken so as to give a good transverse section, the 
longitudinal groove on the dorsal side, which gives rise to the ridge and 
flattened spaces, as described on the internal casts, is clearly shown. 
Species of this genus are so numerous and their features so similar, 
that without nearly perfect specimens for comparison, differences or similar- 
ities can not well be established or described; therefore, not having such in 
hand, I shall not attempt to point out those in which this species differs 
from others. | 
Formation and localities: In the Lower Green Marls at Mullica Hill, and 
in the micaceous clays at their base at Crosswicks and Haddonfield, New 
Jersey. Collection Acad. Nat. Sci., Phila. 
DENTALIUM RIPLEYANUM. 
Plate Lxrx, Fig. 48. 
Deniaium Ripleyanum Gabb: Jour. Acad. Nat. Sci., Phila., 2d ser., vol. 4; Syn- 
opsis, p. 49. 
This species is cited by Mr. Gabb from New Jersey, on p. 49 of his 
Synopsis. I have not been able to find his description of the species, and 
have seen no specimens which I could identify with it. The species is 
named Ripleyanum probably from the locality, or possibly it may have come 
from Eufaula, Alabama, which is of the Ripley group. If the species occur 
in New Jersey at all, it would probably be found at Haddonfield or at 
Croswicks Creek in the dark micaceous clays at those localities, as these 
layers are apparently equivalent to the Ripley and Eufaula beds. The 
species appear to be a small, very slender and almost sharply pointed one, 
with about eight or ten longitudinal ridges, judging from his figures. I 
think it very probable it may have been seen in the Haddonfield layers, as 
it would be very likely to occur there, and if collectors at that locality 
would make a thorough search in these lowest beds of the formation, they 
